1. Field of the Invention
The present invention relates to a substrate support jig for supporting a film-like, flexible substrate, for example, during the operation of mounting electronic components on a substrate; a circuit board production apparatus for mounting and bonding electronic components to a substrate with the substrate being supported by the substrate support jig, whereby the substrate is produced as a circuit board; and a method of producing a circuit board.
2. Description of the Background Art
In recent years, sheet-like flexible substrates have been used in electronic devices, such as mobile phones, in response to the demand for smaller, lighter electronic devices. The flexible substrate is comprised of a resin sheet having printed wiring provided thereon. A plurality of wiring patterns are formed on a flexible substrate, and electronic components, such as ICs, capacitors, resistors, coils, and connectors, are mounted on the wiring patterns, whereby a flexible circuit board is configured. The flexible circuit board is then mounted in a device.
The flexible circuit board has features in that it allows for reduction of substrate thickness and weight, and it can be bended or folded and therefore conforms well to complex shapes. Thus, the moving part of an electronic device does not require a custom joint as is required for non-flexible substrates, enabling a reduction in size of the device.
In particular, even resin sheets with a thickness of the order of 10 μm can be applied, and also flexible substrates composed of a copper foil and having a thickness of the order of 30 microns inclusive of wiring patterns are in actual use.
General mounting equipment is designed to carry substrates composed of materials such as phenolic paper, glass epoxy resin, and ceramic and typically having a side length of 10 mm or greater and a thickness of 0.1 to 4 mm, with both sides of the substrate being supported by belts. Such mounting equipment, however, have difficulty carrying a flexible substrate alone because of the low stiffness of the flexible substrate.
Therefore, conventionally, as shown in FIG. 16, a flexible substrate 43 is fixed to a metal plate 41 which is thick and has high stiffness, with holding clamps 42, for example, and then the metal plate 41 is supplied to special equipment which is a modified form of a carrying system of general mounting equipment. Subsequently, on the flexible substrate 43, cream solder 44 is printed and electronic components 45 are mounted, and then reflow is performed on the cream solder 44, whereby the electronic components 45 are mounted.
However, the workability of the process of fixing flexible substrates 43 to metal plates 41 piece by piece is poor. In addition, since the holding clamps 42 protrude from the top surface of the flexible substrate 43, a special screen is required in the process of screen-printing the cream solder 44. Further, since a plurality of portions of the flexible substrate 43 are held by the holding clamps 42, as shown in FIG. 17, the flatness of the flexible substrate 43 is poor, lowering the closeness of contact with the screen. This degrades the printing quality of the cream solder 44 and causes misposition of the printing or deformation of the cream solder 44, making it impossible to stably perform high-quality mounting.
Moreover, in order to mount a plurality of flexible substrates while ensuring high position accuracy, a plurality of holding clamps become necessary, which complicates the mounting operation as it needs to be done to avoid the misalignment of the substrate position. In addition, since metal plates are being used, special equipment is required as mounting equipment, leading to an increase in production costs.